1. Field of the Invention
The present invention relates generally to a printing method and apparatus, and more particularly to a printing method and apparatus that determines parameters for automatic image correction processing in accordance with inputted images to be printed, that automatically corrects the inputted images with the determined parameters, and that prints the corrected images.
2. Description of Related Art
A conventional printing apparatus such as a digital printer is usually provided with an automatic image correcting function for automatically correcting the differences in color and gradation between images to be printed that have been captured by different cameras, and for automatically correcting an image that has been captured with an improper brightness and/or white balance due to an unsatisfactory automatic exposure (AE) adjustment and/or automatic white balance (AWB) adjustment in the camera, so that the printed images can have a desirable image quality.
Japanese Patent Provisional Publication No. 8-62741 has proposed a gradation correcting apparatus (mainly for a video printer) for automatically determining the features (e.g., back-light or front-light) of a scene with reference to an inputted image and correcting the gradation of the inputted image.
Japanese Patent Provisional Publication No. 62-274889 has proposed an electronic still camera that performs a high-speed consecutive shooting with the color balance being fixed, thus eliminating the differences in the color balance between the consecutive frames even if an object in a saturated color passes the subject area during the high-speed consecutive shooting.
Suppose that a printer determines parameters for the automatic image correction on a frame-by-frame basis for inputted consecutive images and corrects the images on a frame-by-frame basis according to the respective determined parameters in the case that the camera has steadily captured the consecutive images under fixed shooting conditions such as color balance. In this case, for example, if an object in a saturated color has passed the subject area during the consecutive shooting or if the positions of clouds in a blue sky have changed every moment, the printed images are different in color, gradation and gray balance between the frames.
In view of the foregoing, it is an object of the present invention to provide a printing method and apparatus that are able to steadily print a series of related images with color, gradation and gray balance being unchanged.
To achieve the above-mentioned object, the present invention is directed to a printing method, comprising the steps of: determining whether or not inputted images to be printed include a series of images captured under fixed conditions; and if the inputted images are determined as including the series of images in the determining step, calculating a parameter for automatic image correction in accordance with at least one of the inputted images, fixing the parameter, correcting the inputted images in accordance with the fixed parameter, and printing corrected images.
According to the present invention, to print the series of images captured under fixed conditions, the parameter for the automatic image correction is fixed and the images are corrected according to the same fixed parameter. This prevents the differences in the color, gradation and gray balance between the printed images.
Preferably, the printing method is characterized in that the determining step comprises the step of reading additional information concerning the inputted images. The inputted images are determined as including the series of images if the read additional information indicates that the inputted images include the series of images, if the read additional information indicates that the inputted images include the series of images and that shooting time intervals of the inputted images were no more than a preset value, if the read additional information indicates that shooting time intervals of the inputted images were no more than a preset value and that an exposure of the inputted images was fixed, or if the read additional information indicates that the inputted images include the series of images, that shooting time intervals of the inputted images were no more than a preset value and that an exposure of the inputted images was fixed.
Preferably, the parameter for automatic image correction is calculated in accordance with the first image among the series of images or among images to be printed that are selected from the series of images. Alternatively, the parameter for automatic image correction is calculated by averaging parameters, each of which is calculated in accordance with each image of the series of images or in accordance with each of images to be printed that are selected from the series of images. The parameter for automatic image correction may be calculated in accordance with one image designated among the series of images.
The series of images may include consecutive images or images composing a panoramic image.
The present invention is also directed to a printing apparatus, comprising: a determination device which determines whether or not inputted images to be printed include a series of images captured under fixed conditions; a calculator which calculates a parameter for automatic image correction in accordance with at least one of the inputted images, the calculator calculating a common parameter for automatic image correction for the inputted images if the determination device determines that the inputted images include the series of images; an image corrector which corrects the inputted images in accordance with the parameter calculated by the calculator; and a printing device which prints images corrected by the image corrector.
If the inputted images include the series of images, the calculator calculates the common parameter for the automatic image correction, which is used for processing all of the series of images. The image corrector corrects the series of images according to the same common parameter. This prevents the printed images from being different in color, gradation and gray balance.
Preferably, the printing apparatus further comprises a mode selector which selects one of: a mode in which the common parameter is fixed and used in the image corrector if the determination device determines that the inputted images include the series of images; and a mode in which respective parameters for automatic image correction are calculated in accordance with respective images of the series of images and the respective parameters are used in the image corrector even if the determination device determines that the inputted images include the series of images.